added normalize.factors to report and normalization to allow predefined normalization factors

ie for a phospho experiment with factors determined from a global proteome experiment
added conditional formatting (red -> white -> green) to log ratio columns
added function getPeptideModifContext

gathers amino acids around modified residue
modification can be now exported also with name, eg K234me
fix peptide ratio correction
Merge branch 'ptm' of /slow/bioinfo/vcs/git/fbreitwieser/isobar-Rlib into ptm
show context per pep-modif